The GTX was equipped with...
The GTX was equipped with 440 ci of Mopar muscle, and this one is equipped with Edelbrock heads. Multi-point EFI is not a common sight on these beasts.
Stepping up to a modern fuel injection system for your vintage Mopar has always been somewhat like putting a complicated puzzle together. Since no comprehensive bolt-on kits are offered by the players in the market, it has come down to finding an intake you like, adding the injectors, fabbing this and adding that, finding a source for sensors and wiring-and, of course, the ECU-and then just making it work. Get all your favorite injector parts together and set it up-how hard is that? For most guys like us weaned on carburetors, it's pretty hard. What if the whole setup came in a box, with all the parts to make it go? Man, that would be nice, kinda like getting a new toy when you were a kid, and the batteries were already inside.
When we heard rumors that Edelbrock was developing an electronic fuel-injection package to retrofit onto Mopar V8s, it caught our attention. When we found out they already had the big-block system prototyped and running in a test vehicle, we wanted to know more. We snooped around at Edelbrock, where we were informed the system was going through its final calibration and testing program. We were invited to have a look. Edelbrock's Pro-Flow systems have been around for several other applications, and they set the standard for comprehensive EFI retrofit kits. Edelbrock's philosophy is to get the groundwork done, both in terms of the hardware component and electronics, to make the conversion to EFI as simple as possible.
Why go to EFI? The next time you go out to drive your late-model truck, think about how well it works. Twist the key, and it will fire immediately. Put it in gear, and it doesn't die. Step on the gas, and it goes. It starts, runs, and goes-simple desires, really, but the kinds of things you don't always get unless you keep your carb tuned. When was the last time you needed to pop the hood on a factory EFI vehicle and poke around with a screwdriver to get it to idle? Once it's set up, an EFI system can't be beat for reliable and consistent service. Edelbrock's objective was to take care of getting it set up, so the end user can simply enjoy the drive.
Carburetors work on the basis of pressure differential and are primarily dependent on orifice flow for calibration. A carb is fairly rigid in its metering ability, since the flow of fuel and the mixture in the various circuits is established by the orifice sizing of jets, air bleeds, emulsion tubes, and so on. Changes in pressure differential from vacuum or air velocity control the flow through the metering orifices. To alter the fuel curve, the calibrated orifices of the various carb circuits need to be physically changed, as in jet changes, air bleed changes, or altering various drillings in the carb body.
Port-injection fuel delivery...
Port-injection fuel delivery is controlled by fuel pressure and the pulse cycle time of the injector nozzles. The Pro-Flow system comes with 29-lb/hr injectors, with 44-lb/hr units available for engines capable of higher outputs, up to 700 hp.
Fuel injection doesn't directly rely on anything happening at the injector to determine the fuel-flow requirements. Instead, the electronic control unit directly controls the injector output, and in turn relies on sensors to gather information on fuel requirements. The Edelbrock system takes inputs of throttle position, manifold pressure, coolant and intake air temperature, and the readings from an oxygen sensor in the exhaust to calculate the fuel requirements in real time as the engine is operating. More precise control of the quantity of fuel delivered is possible, with injectors mounted in each cylinder's inlet runner, and the fuel distribution becomes as close to ideal as possible.
In addition to controlling the fuel system, modern EFI systems take over the mechanical functions of ignition timing and turn them over to the EFI's electronic control unit. The electronics in the ECU can control timing with more flexibility than the linear action of the springs, weights, and vacuum diaphragm of a mechanical distributor. In controlling both the timing and fuel requirements, an EFI system offers the possibility to manage the engine's systems more accurately than traditional carbs and distributors.
Fuel is plumbed to the injectors...
Fuel is plumbed to the injectors via machined fuel rails conveniently mounted to the intake manifold.
A vacuum-referenced bypass...
A vacuum-referenced bypass fuel-regulator is mounted at the rear of the left fuel rail.
The Pro-Flow system features...
The Pro-Flow system features a four-barrel 1,000-cfm throttle body, which handles only the air metering.